Roadmap Consensus on Carotid Artery Plaque Imaging and Impact on Therapy Strategies and Guidelines: An International, Multispecialty, Expert Review and Position Statement

Abstract

Current guidelines for primary and secondary prevention of stroke in patients with carotid atherosclerosis are based on the quantification of the degree of stenosis and symptom status. Recent publications have demonstrated that plaque morphology and composition, independent of the degree of stenosis, are important in the risk stratification of carotid atherosclerotic disease. This finding raises the question as to whether current guidelines are adequate or if they should be updated with new evidence, including imaging for plaque phenotyping, risk stratification, and clinical decision-making in addition to the degree of stenosis. To further this discussion, this roadmap consensus article defines the limits of luminal imaging and highlights the current evidence supporting the role of plaque imaging. Furthermore, we identify gaps in current knowledge and suggest steps to generate high-quality evidence, to add relevant information to guidelines currently based on the quantification of stenosis.

FIG 1.

Different CT features. A, Plaque ulceration (arrow) is shown with the corresponding macroscopic specimen (F). B, Multiple coarse calcifications (white arrows) within the plaque are visible with the corresponding example in the H&M histologic view (G, arrow points at a calcification). The IPH is visible in H (white arrows) with the corresponding CTA that shows hypodense plaque in C (Hounsfield unit value = 18; white arrow). I, A stable plaque with a prominent fibrous cap with the major part of the plaque with collagenous connective tissue (black arrow) is shown with the corresponding CT section (D, white arrow). E, The presence of a hypodense plaque (Hounsfield unit  = 37) with the corresponding histopathologic slide showing multiple inflammatory cells (J).

FIG 2.

Upper row: Coregistered MPRAGE (A), T2-weighted TSE (B), pre- and postcontrast T1WI TSE MR images (C and D), and a corresponding histologic section (E) of a cross-section of the carotid artery with plaque. A large intraplaque hemorrhage can be recognized as a hyperintense region compared with surrounding muscle tissue in the bulk of the plaque on the MPRAGE image (arrow). Calcification can be identified as a region with hypointense signal on all 4 MR imaging weightings. On the postcontrast T1-weighted TSE image, the region with signal enhancement shows the fibrous cap (between the lumen and intraplaque hemorrhage). The disruption of this enhancement (white arrow) indicates that the fibrous cap is thin or ruptured at this location. Lower row: Coregistered TOF (F), pre- and postcontrast T1-weighted TSE MR images (G and H), and the corresponding histologic section (I) of a cross-section of the carotid artery with a plaque. An LRNC is present in the bulk of the plaque with no or slight contrast enhancement on the postcontrast T1WI (asterisk).

FIG 3.

Roadmap graphic flow chart showing the 4 phases: key mover, early, mainstream, and full adoption. The lighter gray boxes represent the components of the various stages of the roadmap. RCT indicates randomized controlled trial; SOP, standard of practice; US, ultrasound.